A ganglion cyst looks like a round or oval bump sitting just beneath the skin, typically near a joint or tendon. Most are between a quarter inch and an inch and a quarter across, though some grow larger. The skin over the cyst usually looks normal in color, and the bump itself can appear slightly translucent, meaning light can partially pass through it because the cyst is filled with a thick, jelly-like fluid rather than solid tissue.
Shape, Size, and Surface
Ganglion cysts are smooth, rounded lumps that rise up from the tissue beneath the skin. They don’t have irregular edges or rough surfaces. Most sit right on top of a joint or along a tendon, which helps distinguish them from other types of bumps. The skin covering a ganglion cyst typically looks completely normal, with no redness, discoloration, or open sore unless the cyst has been irritated by pressure or friction.
Size varies quite a bit. Some ganglion cysts are as small as a pea, while others grow to roughly the diameter of a golf ball. One distinctive feature is that they change size over time. A cyst may swell noticeably after you’ve been using the joint, then shrink when you rest it. This fluctuation is a hallmark of ganglion cysts and something you won’t typically see with other kinds of lumps.
How It Feels to the Touch
When you press on a ganglion cyst, it can feel either soft and slightly squishy or surprisingly firm, depending on how much pressure the fluid inside is under and where the cyst is located. Cysts on the back of the wrist tend to feel rubbery. Cysts at the base of a finger on the palm side are often very firm, pea-sized nodules that hurt when you grip something. In general, the lump doesn’t move freely under the skin the way a fatty lump would because it’s tethered to the joint capsule or tendon sheath beneath it.
Where They Show Up
The most common spot is the back of the wrist, which accounts for a large share of all ganglion cysts. The palm side of the wrist is the second most common location, followed by the base of the fingers. After the hands and wrists, the ankles and tops of the feet are the next most frequent sites. They can technically develop near any joint, but these locations cover the vast majority of cases.
Mucous Cysts Near the Fingernail
A specific type of ganglion cyst, called a myxoid or digital mucous cyst, forms at the last joint of a finger, right near the nail. These are small, usually about the size of a pencil eraser (5 to 10 millimeters). They have a smooth, shiny surface and often look almost translucent or slightly glassy. They’re typically skin-colored.
What makes these visually distinctive is their effect on the nail. A mucous cyst can press on the nail root and cause a groove or ridge running down the length of the nail. You might also notice slight depressions, color changes in the nail, or splitting. In rare cases, you can lose the nail entirely. If you see a small shiny bump near your fingertip paired with a nail that’s started to look ridged or misshapen, a mucous cyst is a likely explanation.
How to Tell It Apart From Other Lumps
Several common lumps can look similar at first glance, but there are practical differences:
- Lipoma: A soft, rubbery lump that sits under the skin and moves easily when you push it. Lipomas are slow-growing, painless, and tend to appear on the shoulders, neck, back, or stomach rather than directly over a joint. They feel doughy, not firm.
- Sebaceous cyst: A round bump that usually appears on the face, neck, chest, or back. The giveaway is that sebaceous cysts can drain a thick, cheese-like fluid with a strong odor. They can also become red and inflamed, which ganglion cysts rarely do.
- Pilomatrixoma: A small, hard bump under the skin, typically on the face, head, neck, or arms. These feel distinctly hard, almost like a small pebble, compared to the rubbery feel of a ganglion cyst.
The key clue for a ganglion cyst is location. If the bump sits directly over a wrist joint, finger tendon, or ankle joint and changes size with activity, it’s very likely a ganglion cyst rather than one of these alternatives.
The Light Test
One quick way doctors confirm a ganglion cyst is by shining a light through it, a technique called transillumination. Because the cyst is filled with clear, jelly-like fluid, light passes through it and the bump glows. A solid tumor or a blood-filled cyst would block the light and appear dark. This simple test is about 88% accurate at distinguishing fluid-filled cysts from solid masses. You can even try it at home in a dark room with a small flashlight pressed against the bump, though this doesn’t replace a proper evaluation.
Do They Go Away on Their Own?
Roughly 38% to 58% of ganglion cysts disappear without any treatment. They may shrink gradually over weeks or months, or seem to vanish overnight. This is one reason many doctors recommend a watch-and-wait approach if the cyst isn’t causing pain or limiting your movement. The cyst can return even after it disappears, so seeing it shrink and then reappear later is normal and not a sign of something more serious.
If a cyst is painful, interferes with joint movement, or bothers you cosmetically, the two main options are draining the fluid with a needle (aspiration) or surgical removal. Aspiration is quick but has a higher recurrence rate. Surgical removal is more definitive but involves a longer recovery. Neither option is urgent for a typical ganglion cyst.